Features. Applications. RF Power Supply Circuit

Transcription

1 High Performance, Low Noise Dual 500mA ULDO General Description The is a tiny Dual Ultra Low Dropout (ULDO ) linear regulator ideally suited for portable electronics due to its low output noise. The provides two independently controlled high performance 500mA LDOs with typical dropout voltage of 130mV at rated load. In addition, the provides a bypass pin to reduce the output noise. The is designed to be stable with small ceramic output capacitors thereby reducing required board space and component cost. The combination of extremely low dropout voltage, low output noise and exceptional thermal package characteristics makes it ideal for powering RF and noise sensitive circuitry, cellular phone camera modules, imaging sensors for digital still cameras, PDAs, MP3 players and WebCam applications. The ULDO is available in fixed output voltages in the small 8-pin epad MSOP package. Additional voltage options are available. For more information, contact Micrel marketing. Data sheets and support documentation can be found on Micrel s web site at: Features 2.6V to 5.5V input voltage range Ultra low dropout voltage: 500mA Ultra low output noise: 51µV RMS ±2% initial output accuracy Small 8-pin epad MSOP package Excellent Load/Line transient response Fast start up time: 38µs µcap stable with 2.2µF ceramic capacitors Thermal shutdown protection Low quiescent current: 160µA with both outputs at maximum load Current-limit protection Applications Battery-Powered Applications PDAs GPS receivers Portable electronics Portable media players Digital still and video cameras Typical Application RF Power Supply Circuit ULDO is a trademark of Micrel, Inc Micrel Inc Fortune Drive San Jose, CA USA tel +1 (408) fax + 1 (408) January 2011 M

2 Block Diagram January M

3 Ordering Information Part Number (1) Manufacturing Part Number Marking V OUT1 Voltage(V) V OUT2 Junction Temperature Range Package -3.3/2.8YMME -SMYMME 57SM 3.3V 2.8V 40 C to +125 C 8-Pin epad MSOP -3.3/1.8YMME -SGYMME 57SG 3.3V 1.8V 40 C to +125 C 8-Pin epad MSOP -2.8/1.8YMME -MGYMME 57MG 2.8V 1.8V 40 C to +125 C 8-Pin epad MSOP -1.8/1.5YMME -GFYMME 57GF 1.8V 1.5V 40 C to +125 C 8-Pin epad MSOP Notes 1. For other voltage options contact Micrel Marketing. Pin Configuration Pin Description 8-Pin epad MSOP (MME) TOP VIEW Pin Number Pin Name Pin Function 1 VIN Supply Input. 2 GND Ground. 3 BYP Reference Bypass: Connect external 0.1µF to GND to reduce output noise. May be left open when bypass capacitor is not required. 4 EN2 Enable Input (regulator 2). Active High Input. Logic High = On; Logic Low = Off; Do not leave floating. 5 EN1 Enable Input (regulator 1). Active High Input. Logic High = On; Logic Low = Off; Do not leave floating. 6 NC Not internally connected. 7 VOUT2 Regulator Output LDO2. 8 VOUT1 Regulator Output LDO1. epad HS Pad Heatsink Pad internally connected to ground. January M

4 Absolute Maximum Ratings (1) Supply Voltage (V IN ) V to +6V Enable Input Voltage (V EN1, V EN2 ) V to V IN Power Dissipation...Internally Limited (3) Lead Temperature (soldering, 3sec) C Storage Temperature (T S ) C to +150 C ESD Rating (4)... 2kV Operating Ratings (2) Supply Voltage (V IN ) V to +5.5V Enable Input Voltage (V EN1, V EN2 )... 0V to V IN Junction Temperature C to +125 C Junction Thermal Resistance 8-Pin epad MSOP (θ JA ) C/W Electrical Characteristics (5) V IN = V EN1 = V EN2 = V OUT + 1.0V; higher of the two regulator outputs, I OUTLDO1 = I OUTLDO2 = 100µA; C OUT1 = C OUT2 = 2.2µF; C BYP = 0.1µF; T J = 25 C, bold values indicate 40 C T J +125 C, unless noted. Parameter Conditions Min. Typ. Max. Units Output Voltage Accuracy Variation from nominal V OUT Variation from nominal V OUT ; 40 C to +125 C % Line Regulation V IN = V OUT + 1V to 5.5V; I OUT = 100µA %/V Load Regulation I OUT1&2 =100µA to 500mA % Dropout Voltage (6) I OUT1,2 = 50mA mv I OUT1,2 = 100µA 0.1 I OUT1,2 = 500mA Ground Current V EN1 1.2V; V EN2 0.2V; I OUT = 0mA to 500mA V EN1 0.2V; V EN2 1.2V; I OUT2 = 0mA to 500mA µa V EN1 = V EN2 1.2V; I OUT1 = 500mA, I OUT2 = 500mA Ground Current in Shutdown V EN1 = V EN2 = 0V µa Ripple Rejection f = 1kHz; C OUT = 2.2µF; C BYP = 0.1µF 70 f = 20kHz; C OUT = 2.2µF; C BYP = 0.1µF 45 db Current Limit V OUT1 = 0V V OUT2 = 0V ma Output Voltage Noise C OUT = 2.2µF; C BYP = 0.1µF; 10Hz to 100kHz 51 µv RMS Enable Inputs (EN1 / EN2) Enable Input Voltage Logic Low 0.2 Logic High 1.2 V Enable Input Current V IL 0.2V 0.01 V IH 1.2V 0.01 µa Turn-on Time (See Timing Diagram) Turn-on Time (LDO1 and 2) C OUT = 2.2µF; C BYP = 0.1µF µs Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. The maximum allowable power dissipation of any T A (ambient temperature) is P D(max) = (T J(max) T A ) / θ JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. 4. Devices are ESD sensitive. Handling precautions recommended. Human body model 1.5kΩ in series with 100pF. 5. Specification for packaged product only. 6. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 2% below its nominal V OUT. For outputs below 2.6V, the dropout voltage is the input-to-output differential with the minimum input voltage 2.6V. January M

5 Typical Characteristics 100 Ground Current vs. Output Current (V OUT1) 100 Ground Current vs. Output Current (V OUT2) Ground Current vs. Temperature(Dual Outputs) I OUT1=500mA, I OUT2=500mA GROUND CURRENT (μa) V IN=4.3V V OUT1=3.3V GROUND CURRENT (μa) V IN=4.3V V OUT2=2.8V GROUND CURRENT (μa) I OUT1=500mA OUTPUT CURRENT (ma) OUTPUT CURRENT (ma) TEMPERATURE ( C) OUTPUT VOLTAGE (V) μA Output Voltage vs. Input Voltage 500mA V OUT1=3.3V INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) μA Output Voltage vs. Input Voltage 500mA V OUT2=2.8V INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) Output Voltage vs. Output Current V OUT2 V OUT1 V IN=4.3V OUTPUT CURRENT (ma) DROPOUT VOLTAGE (mv) mA Dropout Voltage vs. Temperature 150mA 500mA 50mA DROPOUT VOLTAGE (mv) Dropout Voltage vs. Output Current ` V OUT1=3.3V CURRENT LIMIT (ma) Current Limit vs. Input Voltage V OUT2=2.8V V OUT1=3.3V TEMPERATURE ( C) OUTPUT CURRENT (ma) INPUT VOLTAGE (V) db Power Supply Rejection Ratio mA mA 500mA µA V EN1=V IN=4.74V V OUT1=3.3V -20 C OUT1=2.2µF -10 C BYP=0.1µA FREQUENCY(Hz) NOISE (uv/ Hz) 10 1 Output Noise Spectral Density 0.1 VIN=4.7V VOUT2=1.8V CIN-COUT=2.2µF/6.3V 0.01 IL=250mA Noise Output (10Hz to 100Khz)=51.16µVrms FREQUENCY (Hz) January M

6 Functional Characteristics January M

7 Applications Information Enable/Shutdown The is provided with dual active high enable pins that allow each regulator to be enabled independently. Forcing both enable pins low disables the regulators and sends it into a zero off-mode-current state. In this state, current consumed by the regulator goes nearly to zero. Forcing the enable pin high enables the output voltage. The active high enable pin uses CMOS technology and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output. Input Capacitor The is a high performance, high bandwidth device. Therefore, it requires a well bypassed input supply for optimal performance. A 2.2µF capacitor is required from the input to ground to provide stability. Low ESR ceramic capacitors provide optimal performance at a minimum of space. Additional high frequency capacitors, such as small valued NPO dielectric type capacitors, help filter out high frequency noise and are good practice in any RF based circuit. Output Capacitor The requires an output capacitor of 2.2µF or greater to maintain stability. The design is optimized for use with low ESR ceramic chip capacitors. High ESR capacitors may cause high frequency oscillation. The output capacitor can be increased, but performance has been optimized for a 2.2µF ceramic output capacitor and does not improve significantly with larger capacitance. X7R/X5R dielectric type ceramic capacitors are recommended because of their superior temperature performance. X7R type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. Z5U and Y5V dielectric capacitors change value by as much as 50% and 60%, respectively, over their operating temperature ranges. To use a ceramic chip capacitor with Y5V dielectric, the value must be much higher than an X7R ceramic capacitor to ensure the same minimum capacitance over the equivalent operating temperature range. A unique, quick start circuit allows the to drive a large capacitor on the bypass pin without significantly slowing the turn on time. No-Load Stability Unlike many other voltage regulators, the will remain stable with no load. This is especially important in CMOS RAM keep alive applications. Thermal Considerations The is designed to provide 500mA of continuous current for V OUT1 and 500mA for V OUT2 in a small package. The maximum ambient operating temperature can be calculated based on the output current and the voltage drop across the part. Given that the input voltage is 3.6V, the output voltage is 3.3V for V OUT1, 2.8V for V OUT2 and the output current of 500mA and 500mA respectively. The actual power dissipation of the regulator circuit can be determined using the equation: P D = (V IN V OUT1 ) I OUT1 + (V IN V OUT2 ) I OUT2 + V IN I GND Because this device is CMOS and the ground current is typically <100µA over the load range, the power dissipation contributed by the ground current is < 1% and can be ignored for this calculation. P D = (3.6V 3.3V) 500mA + (3.6V -2.8) 500mA P D = 0.55W To determine the maximum ambient operating temperature of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation: P D(MAX) = T J(MAX) - T A JA T J(max) = 125 C, the maximum junction temperature of the die θ JA thermal resistance = 64.4 C/W. Bypass Capacitor A capacitor can be placed from the noise bypass pin to ground to reduce output voltage noise. The capacitor bypasses the internal reference. A 0.1µF capacitor is recommended for applications that require low noise outputs. The bypass capacitor can be increased, further reducing noise and improving PSRR. Turn on time increases slightly with respect to bypass capacitance. January M

8 Thermal Resistance Substituting P D for P D(max) and solving for the ambient operating temperature will give the maximum operating conditions for the regulator circuit. The junction to ambient thermal resistance for the minimum footprint is 64.4 C/W. The maximum power dissipation must not be exceeded for proper operation. For example, when operating the at an input voltage of 3.6V and 500mA on V OUT1 and 500mA on V OUT2, the maximum ambient operating temperature T A can be determined as follows: Therefore, a 3.3V/2.8V application with 500mA and 500mA output currents can accept an ambient operating temperature of 89.6 C in a small 8 Pin epad MSOP package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the Regulator Thermals section of Micrel s Designing with Low-Dropout Voltage Regulators handbook. This information can be found on Micrel's website at: W = (125 C T A )/(64.4 C/W) T A = 89.6 C January M

9 Typical Application Schematic Bill of Materials Item Part Number Manufacturer Description Qty. C1, C2,C3 C1005X5R0J225M TDK (1) Capacitor, 2.2µF Ceramic, 6.3V, X5R, Size C4 VJ0402Y104KXX Vishay (2) Capacitor, 0.1µF Ceramic, 25V, X7R, Size U1 -xxymme Micrel, Inc. (3) High Performance, Low Noise Dual 500mA ULDO 1 Notes: 1. TDK: 2. Vishay Tel: 3. Micrel, Inc.: January M

10 PCB Layout Recommendations Top Layer Bottom Layer January M

11 Package Information 8-Pin epad MSOP (MME) MICREL, INC FORTUNE DRIVE SAN JOSE, CA USA TEL +1 (408) FAX +1 (408) WEB Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale Micrel, Incorporated. January M